Re: + restore-missing-sysfs-max_cstate-attr.patch added to -mm tree

[Mark Lord]

Arjan van de Ven wrote:
> On Fri, 30 Nov 2007 22:31:17 -0500
> Mark Lord <lkml@xxxxxx> wrote:
>
> > Arjan van de Ven wrote:
> > > On Fri, 30 Nov 2007 22:14:08 -0500
> > > Mark Lord <lkml@xxxxxx> wrote:
> > >
> > > > > in -mm there is.. the QoS stuff allows you to set maximum
> > > > > tolerable
> > > > ..
> > > >
> > > > That's encouraging, I think, but not for 2.6.24.
> > > >
> > > > > latency. If your app cant take any latency, you should set
> > > > > those... and the side effect is that the kernel will not do
> > > > > long-latency C-states or P-state transitions..
> > > > ..
> > > >
> > > > I don't mind the cpufreq changing (actually, I want it to drop in
> > > > cpugfreq to save power and keep the fan off), but the C-states just
> > > > kill this app.
> > > >
> > > > The app is VMware.  I force the max_state=1 when launching,
> > > ah but then its' even easier... and can be done in 2.6.24 already.
> > > VMWare after all has a kernel module, and the latency stuff is in
> > > 2.6.23 and 2.6.24 available inside the kernel already.
> > ..
> >
> > Oh, I'm perfectly happy to write my own kernel module if that's what
>
> all you need to do in your kernel module is call
>
> add_latency_constraint("mark_wants_his_mouse", 5);
>
> or so
..

Dredging up an old regression again now:

The "make my own module to replace /sys/.../max_cstate" doesn't work
for the single-core machine we use a lot around here.

VMware is totally sluggish unless I go to another text window and do this:

   while ( true ); do echo -n ; done

At which point VMware performs well again,
the same as with "echo 1 > max_cstate" in 2.6.23.

Anyone got any suggestions on how to fix this regression
or work around it for 2.6.24 ?

Thanks 


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